cache-assembler fixes prompt-cache invalidation for Claude Code and the Anthropic API. The cache only hits on byte-identical requests, but real traffic breaks that: inconsistent tool-schema ordering, session data leaking into prompts, concurrent requests racing to write the same entry. This proxy fixes all three, with a dedicated Claude Code preset. Measured against the real API (not synthetic): 8.2x cost reduction, $1.33 to $0.16 per 100-turn session. MIT licensed, zero dependencies.
